Category: The Young Earth

Imagine if our world had a diary and on the interesting days, someone pulled out a big book and wrote about it. Day 103 was such a day.

It was about 300 million years ago, just a regular 22.5 hour day and on that lovely sunny morning, on the plains of a future Siberia, a Thursday perhaps, the recent rumblings and shaking of the ground took a turn for the worse.

The newly evolved reptiles had developed into millions of species and the air was filled with insects, some absolute monsters.
The oxygen in the atmosphere had been building up now for quite a while, a far higher concentration than the modest levels that would eventually be the norm for the apes of the future who will enjoy a 24 hour day at 21%, no the oxygen level on this lovely sunny morning was about 35%-40%. A lot of oxygen is a good thing, right?

Well, yes, in the same way your plane’s full tank of fuel is a good thing, right up to when it catches fire, then maybe not so good.
Well, all this oxygen made it possible for creatures that get their oxygen through this skin, insects for example, to grow and grow they did. On this fine sunny morning, there were dragonflies with wingspans like eagles filling the air and let’s not think too much about the local equivalent of mosquitoes.

But aside from the rumblings, life was getting on with what life does and there was no thought for the huge twin asteroids that were already on their way to crash into a future Canada. No matter, that was still a few millions years to go, so certainly no bother for the reptiles and insects.

The first sign of trouble was the smoke and gas arising from a patch of rather large trees. At that moment, the first of many mini volvanos broke the surface over thousands of kilometres of forest. There was going to be trouble and it was not just the trees that were burning and causing all that smoke that blocked out the sun, it was the coal. Vast clouds of thick black choking smoke rose into the upper atmosphere, blocking out the sunlight and quickly spreading around the world.

Yes, the coal, just under the ground, stretching to the horizon in all directions and hundreds of feet thick, was on fire. All that oxygen was not helping either, but why was there so much coal, nearly two million square kilometres of it, as it happens?

An 80-foot wall of coal at a Peabody Energy mine in Powder River Basin in Wyoming. The company filed for Bankruptcy in early April 2016.http://www.peabodyenergy.com/content/2627/media-center/image-gallery

The answer to that is, ‘termites’. Well not exactly, more the lack of termites. What had happened it seems, was that as plant life evolved on land, feeding on sunlight as it does, those that could grow taller got the most sunlight and lived to pass on this trait.
The only way to compete was to grow taller and so lignum had been invented, well, evolved actually a couple of hundred million years before this fine sunny morning. It’s a woody substance that stiffened up the stems of plants and in those days, allowed them to eventually to become trees.

Now here was a problem. You see, lignum is very, uhm, woody and hard to break down, to digest. As it hadn’t been around before, there was no creature large or small, that had evolved the dental hardware to handle it. No bacteria could touch it and termites were millions of years away, so the trees grew and grew, got old and died. That’s all the happened, they just lay there, intact. More trees fell on top and more on top of them, until vast swathes of the earth was covered with dead trees that got compressed and turned in the massive coal deposits of the world as we know it.

As the volcanic action spread across the land, lava flowed and coal burned, for centuries. For a few thousand years, the earth was dark and very cold. There was no sunlight to sustain the plants and most creatures on land and most in the oceans too, turned up their toes in one of the great extinction events we now call the Permian extinction.
Eventually, the lava flows stopped in many places and the fire burned out and the sun came back, just long enough to make use of all the recently released carbon dioxide to heat up the earth, in a hot house of global warming as never seen before. What life had managed to survive the dark and cold was now faced with soaring temperatures and bright sunlight. Actually, it was just a trick and the lava began to flow once more and the whole earth was turned back into a cold dark night that lasted for a few more centuries before doing it again, perhaps as many as seven horrible cycles over several thousand years of hot and cold, dark and light.

Yep, day 103 was a big one and it was all because of those dam termites.

AND, this is just a one line entry in what I believe is the greatest scientific gift poster that anyone could gift to a child. But that’s just my opinion.

Imagine if our world had a diary and on the interesting days, someone pulled out a big book and wrote about it.

Day 83 was such a day.460 million years ago, ocean plant life on the margins begin to colonize the land edges. Mosses, ferns evolve on dry land adapting to take moisture from rain.

The presence of plant life and oxygen create the required conditions for the first fire in our solar system.

Plants aren’t the only things that started out in the photosynthesis business. While the first molecule and the first stirrings of life were a long time ago, early on, the cyanobacteria was on this gig, turning sunlight into energy and pooping out the excess oxygen. This is bad news indeed for the other bacteria that were swimming around in the oceanic soup, because oxygen is poisonous if you are anaerobic, which was everyone really.

All this oxygen also dissolved the iron in the water, which naturally sank to the bottom, forming the foundations for the iron ore business making a few Australians very rich indeed.

Dating this iron and the rock in which it lies, gives a pretty good indication of when the first organisms started photosynthesizing, as there was no oxygen to dissolve the iron before that. The answer is about 580 million years ago.

It also puts a date on something was going to come in handy for future humans, the ultraviolet light reacting with the oxygen making ozone in the stratosphere, a sort of souped up oxygen creating our own sunblock.

A lot of these cyanobacteria lived together happily pumping out oxygen in Western Australia and haven’t left home. (Western Australia is the largest state in Australia at a handy 2.6 million square kilometres or about one million square miles) They reside in a less-than-glamorous grey lump called a Stromatolite, a sort of low rise apartment block about the size of a small car, in the salty waters of Shark Bay in WA.

Evolution worked its magic and some cyanobacteria formed partnerships with other organisms which eventually led to more sophisticated life in the form of green algae.

Obviously being soft, they did not produce much by way of fossils but there is plenty of sturdier stuff further down the tree to be able to work backwards to the first plants, that were rather delicate.

By the time we get to the half billion mark, 500 million years ago, complex life had evolved into millions of different shapes and sizes according to their environment. The first creature with a spine evolved and fish were taking advantage of all the new oxygen that was dissolved in the oceans.

Ten millions years later, while all this evolving was going on, Canada was hit by large asteroid leaving behind a 24 kilometre wide crater, quite a modest impact on the scale of asteroids. No doubt this was not a good day for those creatures living in the immediate area but that didn’t stop groups of photo reactor cells becoming primitive ‘eyes’ in many species.

(The first ‘eyes’ were just cells that react to light. When several or lots happened to be in the same area, they served as a signal that something large was blocking the light. ‘Something large’ often meant ‘something hungry’ and those that took the hint to make a hasty retreat, were the ones that survived to pass on this trait.)

In fact, lots of interesting things were happening. Reef-builders were abundant, as were worms, sponges and numerous other animals. The invertebrates diversified into many new types, including trilobites, starfish, long straight-shelled cephalopods bivalves, nautiloids, and many other types.

Fungi and algae did so well they continue to the present day and while oxygen was in full production, carbon dioxide was hugely more than it is now, something like 25 times as much, but then the earth didn’t have to worry about sea levels and mega storms.

All this synthesizing came on the back of the evolution of complex life, some 180 million years before green algae was the main act. Even so, there were no land plants until 475 million years ago. Bear in mind the earth had been around for most of its life to date. If you imagine the earth time line as a single year, at this point when land plants first got going, it was late November. Put another way, if the earth was like the life of a person, it was already 90 years old before the first plant sprung up. And you thought 460 million years was a long time. It’s just the last 10 years.

We are pretty safe in assuming that the first land plants, which were mostly ferns and mosses had 15 million years to spread out and we know the atmosphere also had oxygen. Now it’s true that matches had not been invented yet, but it’s a fair guess that lightning was pretty common.

Lightening, oxygen and dead plants equals fire. These were probably pretty tame affairs as trees were still another 40 million years in the future.

While the first smoke was wafting across the planet, back in the oceans the first eyes had evolved from the light sensitive cells that were part of the makeup of many creatures.

While the first fires were burning up the dead bacterial and algal mats, these primitive plants were industriously creating the first recognizable soils. They also harboured some arthropods like mites and scorpions but they didn’t have roots or leaves and probably didn’t grow very tall, however, they grew, they survived, they thrived in fact.

By the time a few more million years had passed, the pioneers had developed true roots and leaves and some were getting quite tall, some of the giant versions had developed wood and are the first, the oldest known trees that formed the first forests. It was not long before fire was a part of the natural environment and plants and trees adapted.